chores: use custom github runners

Author: yvan-sraka

nix/github-actions.nix

@@ -1,6 +1,18 @@
 { inputs, ... }:
+let
+  githubPlatforms = {
+    "x86_64-linux" = "large-linux-x86";
+    "aarch64-linux" = "large-linux-arm";
+    "aarch64-darwin" = "macos-latest-xlarge";
+  };
+in
 {
   flake.githubActions = inputs.nix-github-actions.lib.mkGithubMatrix {
-    checks = inputs.nixpkgs.lib.getAttrs [ "x86_64-linux" ] inputs.self.checks;
+    checks = inputs.nixpkgs.lib.getAttrs [
+      "x86_64-linux"
+      "aarch64-linux"
+      "aarch64-darwin"
+    ] inputs.self.checks;
+    platforms = githubPlatforms;
   };
 }